Division of Neurogeriatrics, Center for Alzheimer Research, NVS, Karolinska Institutet, Stockholm, Sweden. anna.matton@ki.se. Division of Clinical Geriatrics, Center for Alzheimer Research, NVS, Karolinska Institutet, Stockholm, Sweden. anna.matton@ki.se. Division of Neurogeriatrics, Center for Alzheimer Research, NVS, Karolinska Institutet, Stockholm, Sweden. Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska University Hospital, Stockholm, Sweden. Division of Clinical Neurosciences, Turku University Hospital, Turku, Finland. Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland. Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland. Joint Municipal Authority for North Karelia Social and Health Services, Joensuu, Finland. Public Health Promotion Unit, Department of Public Health Solutions, Finnish Institute for Health and Welfare, Helsinki, Finland. Division of Clinical Geriatrics, Center for Alzheimer Research, NVS, Karolinska Institutet, Stockholm, Sweden. Institute of Clinical Medicine/Neurology, University of Eastern Finland, Kuopio, Finland. Neurocenter, Neurology Kuopio University Hospital, Kuopio, Finland. Ageing Epidemiology (AGE) Research Unit, School of Public Health, Imperial College London, London, UK. Theme Aging, Karolinska University Hospital, Stockholm, Sweden.